Table or skid lowering mechanism



Nov. 25, 1958 F. G. AUER 2,861,805

TABLE 0R SKID LOWERING MECHANISM Filed July a, 1953 PRINTING CUTTING STACKING RAISE LOWER BRAKE MOTOR ADJUSTABLE TIME DELAY RELAY GEAR G. 3 INVENTOR. RED C I FREDERICK G. AUER BY POSITIVE DRIVE TO MAIN SHAFT ATTORNEY United States Patent 2,861,805 TABLE OR SKID LOWERING MECHANISM Frederick G. Auer, Teaneck, N. J., assignor to Champlain Company, Inc., Bloomfield, N. J., a corporation of New York Application July 8, 1953, Serial No. 366,719 8 Claims. (Cl. 271-38) This invention relates to table or skid lowering mechanisms for receiving and stacking delivered sheets.

It is already known to receive sheets on a table which is so mounted that it is gradually lowered as the sheets are stacked thereon, so that the top of the stack remains at a constant height. For this purpose pawl and ratchet mechanism has been used to lower the table, but difficulty arises in adjusting the motion to conform accurately to the rate required in relation to the thickness of the sheets. In theory the motion desirably should be adjustable in infinitesimal increments, but changes in gear ratios and ratchet wheel teeth will provide only a relatively rough adjustment. Any error, of course, is cumulative.

Another suggestion has been to use a feeler which rests on the top of the stack, and which causes lowering of the table when the stack grows too high. However, such feelers interfere with the feeding of the sheets to the stack, and they also interfere with removal of the sheets from the stack.

The primary object of the present invention is to generaly improve table or skid lowering mechanisms, and to overcome the foregoing disadvantages. More specific objects are to provide a lowering mechanism, the rate of lowering of which is readily adjustable; the adjustment of which is variable in almost infinitesimal increments; and the mechanism for which purpose is simple, trouble-free, and inexpensive.

The present invention takes advantage of the fact that the lowering of the table may be and preferably is intermittent rather than continuous. In accordance with the invention a readily adjustable time delay relay controls the motor. The relay is momentarily energized at predetermined intervals, say once for each fifty sheets delivered. The table lowering motor is then operated for an interval which depends on the closed time set on the time delay relay. This is readily adjustable over a rather wide range, extending say from a fraction of a second to a fraction of a minute. The amount of delay of the relay may be adjusted in exceedingly small increments, despite the very wide overall range of adjustment available, and thus the table lowering is readily adjusted to accommodate a change from very thin sheets to very thick sheets, as well as an unintended and slight and otherwise unnoticed change in the thickness of the particular paper being printed.

To accomplish the foregoing general objects, and other more specific objects which will hereinafter appear, the present invention resides in the elements of the table lowering mechanism, and their relation one to another, as are hereinafter more particularly described in the following specification. The specification is accompanied by a drawing, in which:

Fig. l is a highly schematic elevation, drawn to small scale, of apparatus to which the invention may be applied;

Fig. 2 is a schematic view drawn in perspective and showing one form of table lowering mechanism to which the invention may be applied; and

Fig. 3 is a wiring diagram embodying features of the invention.

Referring to the drawing, and more particularly to Fig. 1, a paper web 12 is drawn from a roll 14, and passes through multi-color printing units 16, 18, 20 and 22. The web is cut into sheets at 24, and the sheets are "ice delivered by a suitable delivery means 26, to a stacking unit 28. This includes the table lowering mechanism to which the invention is applied. Attention is directed to the main shaft 30 which extends longitudinally of and alongside the series of units, and which interconnects the same for synchronous operation. The main driving motor is not shown, but it will be understood that this may be applied to the main shaft 30, or to any one of the units, and in either case the shaft 30 interconnects the various units with a positive drive. The shaft 30 does not drive the stacking unit 28, but it does help control the table lowering rate, as will be described later.

Referring now to Fig. 2 of the drawing, there is a table lowering motor 32, which drives a shaft 34, which in turn drives shafts 36 and 38. These carry sprocket wheels 40, 42, 44 and 46, which in turn control chains 48, 50, 52 and 54. These support a table 56 on which the sheets 58 are stacked. The sheets are delivered to the table by appropriate delivery means, here represented by belt 26. There are vertical stops, not shown, which are engaged by the leading edges of the sheets to register them one above the other.

The drive means between the shaft 34 and the shafts 36 and 38 may include worms 62, 64 and worm gears 66, 68. The gearing need not be irreversible, because the motor 32 may be and preferably is a so-called brake motor of known type. In the usual construction there is an axially movable disc brake at one end, within the motor housing, which disc is normally urged to braking position by compression springs. When the brake magnets are energized they retract the brake against the springs. Thus the entire unit is either electrically energized or dc-energized. When energized the brake is released and the motor operates. When die-energized the brake is applied and the motor is stopped. The use of a brake motor is preferred, not merely to prevent lowering of the table, but also to insure sharply measured increments of operation of the motor each time it is energized for a specified time interval.

In practice the worms 62 and 64 are usually single thread worms which tend to be irreversible (that is, the gear canot drive the worm), but sheets of say 34" x 36" which are stacked 40 high may weigh about a ton, and under such a load the worm gears may drive the worms. This possibility is overcome by using a brake motor.

Referring now to Fig. 3 of the drawing, the terminals of the brake motor are indicated at 32. The particular motor shown is a three-phase motor, and may be connected for either 220 v. or 440 v. operation. This requires nine of the twelve terminals shown. The additional lowest three terminals are for the windings of the brake releasing magnets.

The readily adjustable time delay relay is shown at 70. The spring and dashpot for controlling the amount of time delay has been suggested only schematically at 71, because these relays are conventional and may be purchased on the open market. Various other mechanisms than an air cylinder are used in time delay relays, and any suitable relay may be used here. It is preferred to employ one with a relatively large range of adjustment, say from a fraction of a second to a fraction of a minute, and one the adjustment of which may be made in very time gradations. In one case the relay had a range of a fifth of a second to a tenth of a minute, or a ratio of about 30 to 1, and larger ratios are available. As will be seen, the relay as here used is normally open, and is closed when the relay coil is energized. This in turn energizes the brake motor.

The circuit of the relay coil is itself energized in response to the actuation of switch means, and in the specific arrangement here shown the switch-means comprises both a switch 72 and a relay 74. There further are means to operate the said switch-means only once for a predetermined number of sheets delivered. This is schematically represented by a high ratio gear reduction unit 76, the output end of which is connected by a shaft 78 to a cam 80 which operates the switch 72. The gear reduct1on unit 76 is positively driven from the main shaft previously mentioned in connection with Fig. l, or from any other conveniently available nearby shaft which is itself driven by themain shaft 30, so that the drive of the gear reduction mechanism 76 is dependent on the number of sheets delivered. In the present case this con nection is symbolized by a chain and sprocket connection 82 but any other form of positive drive may be used.

The intermediate relay 74 is employed because the motion of the cam 80 may be very slow, and, for some adjustments of the time delay relay may keep the switch 72 closed for a time greater than the desired adustment interval of relay 70. It will be understood that the time delay relay remains closed when the coil is energized for even an instant, and does not open until the desired time has elapsed. In order to make available the full range of time adjustment, it is desirable that the energization of the relay magnet be kept exceedingly brief, and it is for this purpose that the relay 74 is interposed.

Relay 74- is a normally closed relay, and when the camoperated switch 72 is closed the relay 7 4 is energized and its contacts are opened soon, thereby deenergizing the relay 70. However, although the relay 74 acts fast, there is necessarily a slight delay in the opening of its contacts, and during that momentary delay a brief surge of current rushes through the relay coil 70, thus actuating thedatter. With this arrangement the coil of the relay '70 is energized for only an instant, even though the cam may turn very slowly, and the switch 72 remain closed for a long time, it being recalled that the gear reduction in the unit 76 may be of the order of 50 to 1.

Because the brake motor 32 is a three-phase motor, and because its power requirements may be heavier than is desirable for passage through the contacts of the time delay relay 70, the latter preferably controls another and L heavier relay 84. This relay controls three contacts which are in series between the three-phase supply line 86 and the brake motor 32. It will be evident that closing of the time delay relay 70 energizes relay magnet 34 and thus energizes the brake motor.

The relay magnets are all energized through a separate power supply, which may be an ordinary single-phase 110 volgssupply line, the terminals for which are indicated at The wiring diagram of Fig. 3 includes other features which may be described briefly. The table may be raised or lowered under manual switch control. For this purpose there are switches 90 and 92, here shown as pushbutton switches, which are marked Raise and Lower. These buttons each preferably have four contacts i11- stead of two, the upper contacts being normally closed. These extra contacts are used to interlock the switches so that no difficulty' will arise in the event that both pushbuttons are pushed down at once.

When the Lower button 92 is depressed current flows through wire 94, the upper contacts of button 590, the lower contacts of button 92, wire 96, and wire 98, to the main relay magnet 84. The return is by way of conductor 100. Thus the brake motor 32 will be operated to lower the table.

To raise the table the motor must be operated in reverse direction. With a three-phase motor this is done by reversing one phase, and another main relay 102 is provided for this purpose. If the wiring is traced it will be seen that closing of relay 102 energizes the brake motor 32, but with two of the three wires interchanged compared with relay 84, thus causing the motor to operate in reverse direction. If the Raise button 90 is depressed, control current flows through conductors )4 and 104, through the upper contacts of button 92, thence 4 through the lower contacts of button 90, and thence through conductors 106 and 108 to the main relay coil 102, thus closing the relay. The current returns by way of conductor 100.

To prevent overtravel of the table the mechanism preferably includes limit switches. An upper limit switch is shown at 110, and a lower limit switch at 112. It will be understood that these are mounted on the stationary frame (28 in Fig. 1) within which the table is moved up and down, and are so positioned as to be engaged by the table when it reaches a desired upper limit or a desired lower limit. The upper limit is ordinarily set at the height the table should be when the first sheet is to be delivered. The lower limit is set at a desired point, often at a point near the floor. On examination of the diagram in Fig. 3 it will be seen that the upper limit switch 110 is directly in series with the main relay 102 for raising the table, so that opening of the limit switch will stop the motor. Similarly, the lower limit switch 112'is directly in series with the main relay 84 for lowering the table, so that opening of the limit switch will stop the motor.

I have so far referred to the lowering of a table, but it will be understood that exactly the same mechanism may be employed to lower a skid or pallet. Indeed in simplest form the skid may simply rest on the table, and the upper limit switch may be so located as to limit upward movement at a point Where the skid, rather than the table, is opposite the delivery point when empty. When a desired number of sheets have been piled on the skid, the skid with the sheets may be removed by means of a conventional fork truck, the fork of which is run beneath the skid in the usual way.

It will also be understood that While I have referred to the use of a reduction gear unit at 76 to operate the cam 80, the desired result may equally well be obtained by other means. Essentially the device acts as a counter to count out a desired number of sheets, say fifty or one hundred sheets, before energizing the motor. It is evident that a pawl and ratchet wheel, or digit wheel counters of the usual type employing Geneva gear and pinion arrangements, or other forms of counter, might equally well be employed for the same purpose.

It is believed that the construction and operation, as well as the advantages of my improved table or skid lowering mechanism, will be apparent from the foregoing detailed description. It will also be apparent that while I have shown and described the invention in a preferred form, changes may be made in the mechanism shown, without departing from the scope of the invention, as sought to be defined in the following claims. In the claims, I have, for convenience, referred to lowering of a table, but it will be understood that this is intended to include the lowering of a removable skid or pallet as well as a table. In the claims I have, for convenience, referred to the counting of the sheets as determined by reduction gearing, but this is not intended to exclude a pawl and ratchet wheel, or Geneva gear and pinion mechanism, or other equivalent counting mechanism for the same purpose.

I claim:

1. Lowering mechanism for receiving a relatively large stack of sheets, said lowering mechanism comprising a table to receive the sheets, an electrically controlled drive means to lower the table by a succession of slight inter-' mittent movements, an adjustable time delay relay for the drive means set for a short increment of time, said relay having an operating magnet .and having relay contacts operated by said magnet, a relay circuit for said relay magnet, switch means to repeatedly close the relay magnet circuit in order to close the relay contacts in order to energize the drive means in intermittent short increments, and means to repeatedly operate said switch means once for each accumulation of sheets to form a groupof sheets containing a predetermined number of sheets which number is very srnall compared to the number in a full stack of sheets, the average rate of lowering of the table being adjusted by adjusting the duration of the short increment of closed time of the aforesaid time delay relay, and the closed time being at most an amount less than the time required to accumulate one of the aforesaid small groups of sheets.

2. Lowering mechanism for receiving a relatively large stack of sheets from apparatus including a shaft rotated in proportion to the number of sheets discharged from said apparatus, said lowering mechanism comprising a table to receive the sheets, an electrically controlled drive means to lower the table by a succession of slight intermittent movements, a readily adjustable time delay relay for the drive means set for a short increment of time, said relay having an operating magnet and having relay contacts operated by said magnet, a relay circuit for said relay magnet, means to repeatedly momentarily close the relay magnet circuit in order to close the relay contacts to energize the drive means in intermittent short increments, and reduction gearing driven by the aforesaid shaft to operate said means once for each accumulation of sheets to form a group of sheets containing a predetermined number of sheets as determined by the reduction gearing which number is very small compared to the number in a full stack of sheets, the average rate of lowering of the table being adjusted by adjusting the duration of the short increment of closed time of the aforesaid time delay relay, and the closed time being at most an amount less than the time required to accumulate one of the aforesaid small groups of sheets.

3. Lowering mechanism for receiving a relatively large stack of sheets from apparatus including a shaft rotated in proportion to the number of sheets discharged from said apparatus, said lowering mechanism comprising a table to receive the sheets, a brake motor to lower the table by a succession of slight intermittent movements, a relay for the motor, a circuit including a readily adjustable time delay relay for the motor relay set for a short increment of time, means to repeatedly close the time delay relay circuit in order to close the relays in order to energize the motor and release the brake in intermittent short increments, and reduction gearing driven by the aforesaid shaft to operate said means once for each accumulation of sheets to form a group of sheets containing a predetermined number of sheets as determined by the reduction gearing which number is very small compared to the number in a full stack of sheets, the average rate of lowering of the table being adjusted by adjusting the duration of the short increment of closed time of the aforesaid time delay relay, and the closed time being at most an amount less than the time required to accumulate one of the aforesaid small groups of sheets.

4. Lowering mechanism for receiving a relatively large stack of sheets, said lowering mechanism comprising a table to receive the sheets, an electrically controlled drive means to lower the table by a succession of slight intermittent movements, a circuit including a readily adjustable time delay relay for the drive means set for a short increment of time, switch means to repeatedly close the relay circuit in order to close the relay to energize the drive means in intermittent short increments, said switch means including a normally open switch connected to the coil of a normally closed relay the contacts of which are in series with the time delay relay, whereby the latter is energized only momentarily, and means to repeatedly operate said switch means once for each accumulation of sheets to form a group of sheets containing a predetermined number of sheets which number is very small compared to the number in a full stack of sheets, the average rate of lowering of the table being adjusted by adjusting the duration of the short increment of closed time of the aforesaid time delay relay, and the closed time being at most an amount less than the time required to accumulate one of the aforesaid small groups of sheets.

5. Lowering mechanism for receiving a relatively large stack of sheets from apparatus including a shaft rotated in proportion to the number of sheets discharged from said apparatus, said lowering mechanism comprising a table to receive the sheets, a brake motor to lower the table by a succession of slight intermittent movements, a relay for the motor, a circuit including a readily adjustable time delay relay for the motor relay set for a short increment of time, means to repeatedly close the time delay relay circuit in order to close the relays in order to energize the motor and release the brake in intermittent short increments, said means including a normally open switch connected to the coil of a normally closed relay the contacts of which are in series with the time delay relay, whereby the latter is energized only momentarily, and reduction gearing driven by the aforesaid shaft to operate said means once for each accumulation of sheets to form a group of sheets containing a predetermined number of sheets as determined by the reduction gearing which number is very small compared to the number in a full stack of sheets, the average rate of lowering of the table being adjusted by adjusting the closed time of the aforesaid time delay relay, and the closed time being at most an amount less than the time required to accumulate one of the aforesaid small groups of sheets.

6. Apparatus as defined in claim 1 including also reversing switch means for reversing the direction of the motor, a manual raise switch means for controlling the motor to raise the table, and a manual lower switch means to control the motor to lower the table, said latter means bypassing the aforesaid adjustable time delay relay, and in which the circuit of the raise switch includes a raise limit switch which is opened by the table when it reaches a desired upper limit, and in which the circuit of the lower switch and of the time delay relay include a lower limit switch which is opened when the table reaches a desired lower limit.

7. Apparatus as defined in claim 2 including also reversing switch means for reversing the direction of the motor, a manual raise switch means for controlling the motor to raise the table, and a manual lower switch means to control the motor to lower the table, said latter means bypassing the aforesaid adjustable time delay relay, and in which the circuit of the raise switch includes a raise limit switch which is opened by the table when it reaches a desired upper limit, and in which the circuit of the lower switch and of the time delay relay include a lower limit switch which is opened when the table reaches a desired lower limit.

8. Apparatus as defined in claim 5, including also reversing switch means for reversing the direction of the motor, a manual raise switch means for controlling the motor to raise the table, and a manual lower switch means to control the motor to lower the table, said latter means bypassing the aforesaid adjustable time delay relay, and in which the circuit of the raise pushbutton switch includes a raise limit switch which is opened by the table when it reaches a desired upper limit, and in which the circuit of the lower switch and of the time delay relay include a lower limit switch which is opened when the table reaches a desired lower limit.

References Cited in the file of this patent UNITED STATES PATENTS 1,833,292 Krick Nov. 24, 1931 1,918,960 Elberty July 18, 1933 2,156,032 Seybold Apr. 25, 1939 2,178,879 Mikes Nov. 7, 1939 2,205,767 Lamb June 25, 1940 2,375,241 Lindgren May 8, 1945 2,406,489 Case Aug. 27, 1946 2,548,028 Klammer Apr. 10, 1951 

